Structure of Heart and Blood Vessels

Question 1

Give the order of the loop of blood vessels coming from the heart and looping back to the heart.

Answer 1

Heart, elastic arteries, muscular arteries, arterioles, capillaries, venules, veins, muscular veins, heart

Question 2

Describe the three-layered structure of blood vessels.

Answer 2

. Tunica intima (innermost)- simple squamous epithelia
. Tunica media (middle)- cardiac/smooth muscle
. Tunica adventitia (outermost)- connective tissue

Question 3

What is the blood supply of the myocardium?

Answer 3

Coronary arteries

Question 4

How can you identify the tunica media under the microscope?

Answer 4

. Darker brown than tunica intima
. Brown/beige background of collagen
. Darker brown lines of smooth muscle
. Black wavy lines of elastin

Question 5

What are vasa vasorum?

Answer 5

Blood vessels of the blood vessels

Question 6

How can you identify the tunica adventitia under the microscope?

Answer 6

Pale loose connective tissue

Question 7

How do you define an arteriole?

Answer 7

A vessel with 1-3 smooth muscle cell layers

Question 8

Which vessels experience the greatest resistance to blood flow?

Answer 8

Small arteries and arterioles because these vessels are most involved in blood flow regulation

Question 9

What is the function of pericytes?

Answer 9

They assist in the maintenance and support of capillaries

Question 10

What is the difference between continuous and fenestrated capillaries?

Answer 10

Continuous capillaries have a continuous line of squamous epithelia linked by tight and adherens junctions, whereas fenestrated capillaries have numerous pores in the epithelia (their barrier to the interstitium is the basement membrane, e.g. in the kidneys)

Question 11

What are sinusoids? Where are they found?

Answer 11

. Wide capillaries found in liver and spleen
. Several erythrocytes in diameter
. Pores in endothelial cells and basement membranes to allow plasma to reach liver/spleen
. Allows faster exchange of components

Question 12

Can capillaries regenerate and adapt?

Answer 12

Yes, they can regenerate when damaged (pericytes repair them) and adapt to demand by enlarging their diameter if needed

Question 13

Compare the lumen diameter of capillaries and venules.

Answer 13

Venules have a larger diameter than capillaries

Question 14

What are valves in the veins made from?

Answer 14

Tunica intima

Question 15

Describe how the vein-artery-vein triplet aids blood flow back to the heart? Give system that helps this kind of blood flow.

Answer 15

. Artery flanked by two veins
. Pulsations from artery compress veins and help push blood up to the heart

. Blood flow in veins can also be helped by muscle contraction e.g. when walking the muscle sin your legs contract and squeeze the veins

Question 16

What is the portal system? What does the portal vein do?

Answer 16

. Connects two capillary beds (e.g. portal vein links capillary beds of digestive system and spleen directly to the capillary bed (sinusoids) of the liver

Question 17

What is an anastomosis? Give an example of where these can be found.

Answer 17

. A direct link between and artery and an artery, a vein and a vein, or an artery and a vein, without a capillary bed in between
. E.g. vein-vein anastomoses in the superficial veins of the hand